Optically reproducing pick-up heads for reading information stored on a storage medium, such as a compact disk, are well know. Unfortunately, while they are sufficient for reading data, they cannot write data to the storage medium.
Recent developments in phase changing materials have opened up the possibility of read/write optical devices. The materials developed change between two phases, one more reflective than the other. This permits data to be stored digitally and recovered in a manner similar to the current method of scanning pits and lands.
In conventional read systems, light is projected onto the surface of a data storage medium containing pits and lands. The changes in light intensity through the conductivity mechanism of a light receiving assembly informs the system of a transition from a pit to a land and vice-versa. In operation, the pits scatter the light, and the lands reflect the light. These changes are detected by the optical device and register in a digital form. By using phase changing materials, the material can be written to by changing portions between phases. The different phases function in a manner similar to pits and lands, with one phase scattering the light and the other reflecting it. Attempts at producing optical write devices include providing phase change materials which change between phases by the application of heat. Heat is supplied by energy from the beams of edge emitting lasers. While multi-spacial mode edge emitting diode lasers provide a sufficiently powerful laser beam, the intrinsically severe astigmatism, mode partition, and mode hopping noise make it unsuitable for optical writing. The severe astigmatism makes it difficult to focus the laser beam down to an appropriate spot size and makes it difficult to provide uniform energy distribution for changing the material's phase. Mode partition and hopping noise further effect the quality of data recording.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide new and improved optical data read/write apparatus.
Another object of the invention is to provide compact optical data read/write apparatus.
And another object of the invention is to provide an optical data read/write device employing a relatively high powered VCSEL.
Still another object of the present invention is to provide a optical data read/write device which will produce a more efficient phase change.
Yet another object of the invention is to provide an optical data read/write device with a lower cost due to simplified device fabrication processes.